[A retrospective study of six patients with late-onset Pompe disease]. / Forme adulte de la maladie de Pompe: à propos de six cas de la région du Languedoc-Roussillon.

ABSTRACT

INTRODUCTION: Pompe's disease, also called glycogen storage disease type II or acid maltase deficiency, is an autosomal recessive disease caused by an enzymatic deficiency of acid-alpha-glucosidase (GAA). This deficiency causes an accumulation of intralysosomal glycogen in different organs. The classic form appears in the newborn with a very severe hypotonia and cardiomyopathy, which lead to death before age two. Less frequently, the disease appears only in childhood or in adult life, so called late-onset Pompe's disease. This form causes a very progressive limb-girdle myopathy and restrictive respiratory failure. The diagnosis is based on a low level of GAA either in the muscle biopsy or in the leucocytes. We report six cases of late-onset Pompe's disease from the Languedoc-Roussillon district. METHOD: Our work was a retrospective analysis of all cases of Pompe disease diagnosed in adults between 1975 and 2006 at the Montpellier and Nîmes University Hospital. We describe the clinical presentation and course of this form and explain the diagnostic approach. Results. The mean age at onset was 44.3 years (range 36-60 years). The first symptom was fatigability (50%), gait difficulty (50%) and dyspnea (16%). The mean delay from symptom onset to diagnosis was 8.4 years (range 17 years). Fatal outcome due to respiratory failure was noted in three patients. The mean time between symptom onset and death (four patients) was 20.75 years (range 37 years). The diagnosis was made on the muscle biopsy showing a low level of GAA. Muscle was strictly normal on the morphologic study in one patient, pointing out the requirement for enzymatic analysis. Molecular confirmation was available in one patient. DISCUSSION: Late-onset Pompe's disease is a possible cause of limb-girdle myopathy. Respiratory involvement is a characteristic feature. Enzymatic assay of GAA activity on the muscle biopsy is required for certain diagnosis. CONCLUSION: It is very important to recognize the adult form of Pompe's disease, a possible cause of limb-girdle myopathy, in order to search for respiratory failure and propose non-invasive ventilation if necessary. Moreover, substitutive therapy (recombinant acid-alpha-glucosidase) has shown efficiency for the classical infantile form of Pompe's disease and such treatment could be proposed for the adult form if larger studies confirm its efficacy.